Inverter system enabling self-configuration

ABSTRACT

A method of configuring an installed energy harvesting device to comply with a local grid connection standard is provided. The method identifies a local grid connection standard for an energy harvesting device that has been installed in a physical installation. The method then configures the energy harvesting device to apply the identified grid connection standard. To identify the local gird connection standard, the method determines a physical location for the installation of the energy harvesting device. The method then identifies the local grid connection standard based on the determined physical location.

CROSS-REFERENCES TO RELATED APPLICATIONS

This Application is a continuation of U.S. application Ser. No.14/142,693, filed Dec. 27, 2013, which claims the benefit of U.S.Provisional Patent Application 61/749,251 filed Jan. 4, 2013, all ofwhich are incorporated by reference herein.

BACKGROUND OF THE INVENTION

Many micropower generation systems, such as those in the home, typicallyinclude one or more of a number of solar cells, wind turbines, combinedheat and power systems and other similar systems. The micropowergeneration systems generate electricity. The generated electricity isconverted into useable voltage and current suitable for localconsumption, for example 240V at 50 Hz or 110V at 60 Hz. However, thesemicropower generation systems often generate more power than is actuallyneeded for local consumption. If the micropower generation systems wereconnected to the alternating current (AC) gird, from which power isnormally drawn, this surplus power could be sent back to the AC grid.

Micropower generation systems often include inverters that are used togenerate an AC output from a direct current (DC) input. The invertersare generally located within the proximity of the power source (solarcells, wind turbine, etc.) and connected to the AC grid mains remotely.Among various inverters, a solar inverter converts the variable DCoutput of a photovoltaic (PV) solar panel into a utility frequency ACthat can be fed into a commercial electrical grid or used by a local,off-grid electrical network.

In recent years there has been a re-emergence of interest inmodule-integrated electronics. The solar micro-inverter in particularhas been noted as a product that has a number of benefits over theexisting conventional solutions. A solar micro-inverter converts DCelectricity from a single solar panel to AC. The electric power fromseveral micro-inverters is combined and fed into an existing electricalgrid. Unlike conventional string inverter devices, each micro-inverteris connected to a single solar panel rather than multiple solar panels.

The benefits of an energy harvesting system based on micro-invertersinclude: improved energy harvest over the life of the installation,particularly in scenarios of shading or other causes of mismatch insolar PV installations; and low voltage DC (less than 80V from a singlepanel), which is safer and significantly reduces arcing faults.Additional benefits of an energy harvesting system based onmicro-inverters also include the ability to pinpoint failures orproblems with solar panels (or solar modules), and the scalability byadding panels to an installation. The installation process itself isalso extremely easy and can be considered as a plug and play method.Solar micro-inverters enable true plug and play installation of solar PVmodules. The ease with which these can be installed is a major sellingpoint for the solar industry. In the discussion that follows, the term“inverter” is used to describe all electrical power converters thatchange DC to AC, including string inverters and micro-inverters.

Because the inverters are fed into an existing electrical grid, theyhave to conform to the grid connection standard used by the localelectrical grid. For example, the inverters must synchronize with thefrequency of the electrical grid, the AC current produced by theinverters must be within the required voltage range of the grid, and soon. Different countries have different utility requirements. As aresult, inverters manufactured for different countries must beconfigured differently in order to function properly.

Currently, the inverters are configured in the factory, where they aremanufactured and labeled. This adds an extra step in the manufacturingprocess. Moreover, once the inverters are manufactured and configured,they have to be managed separately for different countries or differentgrid connection standards. The manufactured inverters usually do not goimmediately from the factory to the end customer. They are usuallystored in several warehouses in different regions around the world,waiting to be ordered and distributed. FIG. 1 conceptually illustratesthe current approach of manufacturing and distributing inverters todifferent countries by configuring inverters at the factory. As shown inthe figure, a factory 105 manufactures and configures differentinverters based on different grid connection standards for differentcountries. The configured inverters are stored in two warehouses 110 and115, and distributed to five different countries, i.e., country 1-5.

The factory 105 produces and configures the inverters 1-5, each of whichis configured to comply with a particular grid connection standard of aparticular country. For example, the inverter 1 is configured to complywith the grid connection standard of country 1, the inverter 2 isconfigured to comply with the grid connection standard of country 2, andso on. Once the inverters are produced and configured in the factory105, they are stored in warehouses 110 and 115. A warehouse storesseveral different kinds of inverters. Each kind of inverter isconfigured for the grid connection standard of a particular country. Forexample, warehouse 110 stores three different kinds of inverters, i.e.,inverter 1-3 for country 1-3. The warehouse 115 stores three differentkinds of inverters, i.e., inverter 3-5 for country 3-5. Inverters withthe same configuration may be stored in different warehouses. Forinstance, inverter 3 is stored in both warehouses 110 and 115. Thedifferent kinds of inverters are distributed to their correspondingcountries when ordered by customers. For example, inverter 1 isdistributed to country 1; inverter 2 is distributed to country 2, and soon. Because the same kind of inverters may be stored in differentwarehouses, a country may receive inverters configured to comply withits grid connection standard from multiple warehouses. For instance,country 3 receives inverter 3 from both warehouses 110 and 115.

As illustrated in FIG. 1, in order to ensure sufficient supply for eachcountry and each grid connection standard, the warehouses must carry alot of different stocks and treat different inverters differently basedon demand forecasting and many other factors. When the manufacturerneeds to supply inverters to many different countries or different gridconnection standards, the management of the inventory and distributionof different inverters become very complicated.

BRIEF SUMMARY OF THE INVENTION

Some embodiments of the invention provide a method of configuring aninstalled energy harvesting device to comply with a local gridconnection standard. The method identifies a local grid connectionstandard for an energy harvesting device that has been installed in aphysical installation. The method then configures the energy harvestingdevice to apply the identified grid connection standard.

To identify the local gird connection standard, the method of someembodiments determines a physical location for the installation of theenergy harvesting device. The method then identifies the local gridconnection standard based on the determined physical location.

To determine the physical location of an installed energy harvestingdevice, the method of some embodiments utilizes a global positioningsystem (GPS) receiver equipped on the energy harvesting device. In someembodiments, the physical location for the installed energy harvestingdevice is determined by receiving a user input. In some embodiments, themethod determines the physical location of the installed energyharvesting device by receiving the physical location from acommunication gateway. Other embodiments determine the physical locationof the installed energy harvesting device by receiving the physicallocation from a handheld installation device located near the physicalinstallation.

In some embodiments, the handheld installation device determines thephysical location of the installed energy harvesting device by using aGPS receiver equipped on the handheld device to identify the physicallocation of the handheld device. The physical location of the handheldinstallation device is then treated as the physical location of theinstalled energy harvesting device because they are located physicallynear each other. In some embodiments, the handheld installation deviceidentifies the physical location of the installation by receiving a userinput.

Instead of receiving a physical location of the installation, the methodof some embodiments receives a local grid connection standard from ahandheld installation device located near the physical installation ofthe energy harvesting device. The handheld installation deviceidentifies the local grid connection standard based on the physicallocation of the installation. In some embodiments, the physical locationof the installation is determined by receiving a user input on thehandheld device. In other embodiments, the installation location isdetermined by receiving a GPS coordinate through a GPS receiver equippedon the handheld device.

The method of some embodiments receives the local grid connectionstandard from a communication gateway that connects the installed energyharvesting devices to a communication network. The communication gatewayof some embodiments identifies the local grid connection standard basedon a physical location of the communication gateway determined by a setof networking parameters of the communication network. The communicationgateway then sends the identified grid connection standard to theinstalled energy harvesting device. In some embodiments, the set ofnetworking parameters includes the Internet Protocol (IP) address of thecommunication gateway. The set of networking parameters of someembodiments includes the location of the nearest Wi-Fi access point orthe location of the nearest cellular tower. In some embodiments, thelocal grid connection standard identified by the communication gatewayis confirmed by a user input before being sent to the installed energyharvesting device.

In some embodiments, each energy-harvesting device includes an inverterfor converting energy from photovoltaic modules into AC output. Theenergy harvesting device of some embodiments includes a power converterfor converting DC power from a photovoltaic device to AC electricity anda controller for configuring the power converter based on a local gridconnection standard after the energy harvesting device has beeninstalled. The controller of some embodiments includes at least oneprocessor. In some embodiments, the energy-harvesting device furtherincludes a GPS receiver for determining the physical location of theinstallation. The controller then identifies the local grid connectionstandard based on the physical location determined by the GPS receiver.

In some embodiments, the controller of the energy harvesting deviceidentifies the local grid connection standard through searching a datastructure that contains information regarding all grid connectionstandards. Different embodiments store the data structure differently.In some embodiments, the data structure is stored on the energyharvesting device. In other embodiments, the data structure is stored onanother device and is accessable to the controller through acommunication network. The data structure of some embodiments is a gridconnection standards lookup table. The grid connection standards lookuptable contains all the grid connection standards and the correspondinggeographic regions for each grid connection standard. In someembodiments, instead of identifying the grid connection standard byitself, the controller of the energy harvesting device receives theappropriate grid connection standard from a device outside of the energyharvesting device.

The energy harvesting device of some embodiments includes acommunication module. In some embodiments, the controller of the energyharvesting device uses the communication module to communicate withother devices in a communication network.

The energy harvesting device of some embodiments is equipped withcommunications devices such as wireless transceivers as part of thecommunication module. In some embodiments, instead of or in conjunctionwith using wireless communication, the communication module uses thepower line to communicate with other devices in the communicationnetwork.

The preceding Summary is intended to serve as a brief introduction tosome embodiments of the invention. It is not meant to be an introductionor overview of all inventive subject matter disclosed in this document.The Detailed Description that follows and the Drawings that are referredto in the Detailed Description will further describe the embodimentsdescribed in the Summary as well as other embodiments. Accordingly, tounderstand all the embodiments described by this document, a full reviewof the Summary, Detailed Description and the Drawings is needed.Moreover, the claimed subject matters are not to be limited by theillustrative details in the Summary, Detailed Description and theDrawing, but rather are to be defined by the appended claims, becausethe claimed subject matters can be embodied in other specific formswithout departing from the spirit of the subject matters.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth in the appendedclaims. However, for purpose of explanation, several embodiments of theinvention are set forth in the following figures.

FIG. 1 conceptually illustrates the current approach of manufacturingand distributing inverters to different countries by configuringinverters at the factory.

FIG. 2 conceptually illustrates a new approach of manufacturing anddistributing inverters in different countries by configuring theinverters after installation in some embodiments of the invention.

FIG. 3 conceptually illustrates a typical installation for an array ofinverters.

FIG. 4 illustrates a block diagram of an inverter that can be used toimplement the array of inverters of FIG. 3.

FIG. 5 conceptually illustrates an inverter configuration module of someembodiments.

FIG. 6 conceptually illustrates a process performed by some embodimentsto configure an inverter to comply with an appropriate grid connectionstandard based on the installation location of the inverter.

FIG. 7 conceptually illustrates a process performed by some embodimentsto configure a set of installed inverters through a communicationgateway.

FIG. 8 conceptually illustrates an installation for an array ofinverters that use equipped GPS receivers to configure themselves insome embodiments of the invention.

FIG. 9 conceptually illustrates using a handheld device to configure aset of installed inverters.

FIG. 10 conceptually illustrates using a handheld device equipped with aGPS receiver to configure a set of installed inverters.

FIG. 11 conceptually illustrates a process performed by some embodimentsto configure a set of installed inverters by a handheld device to complywith an appropriate grid connection standard.

FIG. 12 illustrates an example of a set of parameters included in a gridconnection standard.

FIG. 13 conceptually illustrates an electronic system with which someembodiments of the invention are implemented.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, numerous details are set forth for thepurpose of explanation. However, one of ordinary skill in the art willrealize that the invention may be practiced without the use of thesespecific details. In other instances, well-known structures and devicesare shown in block diagram form in order not to obscure the descriptionof the invention with unnecessary detail.

Some embodiments of the invention provide a method of configuring aninstalled energy harvesting device to comply with a local gridconnection standard. The method identifies a local grid connectionstandard for an energy harvesting device that has been installed in aphysical installation. The method then configures the energy harvestingdevice to apply the identified grid connection standard.

To identify the local gird connection standard, some embodimentsdetermine a physical location for the installation of the energyharvesting device. These embodiments then identify the local gridconnection standard based on the determined physical location.

FIG. 2 conceptually illustrates a new approach of manufacturing anddistributing inverters to different countries by configuring theinverters after installation in some embodiments of the invention. Asshown in the figure, because the inverters are configured at the fieldafter installation, a factory 105 manufactures the same generic inverter205 for all countries. The generic inverters 205 are stored in twowarehouses 110 and 115, and distributed to five different countries,i.e., country 1-5.

The factory 105 produces the generic inverter 205, each of which can beconfigured after installation to comply with any grid connectionstandard of any country. Once the inverters are produced in the factory105, they are stored in warehouses 110 and 115. Each of the warehouses110 and 115 stores the same generic inverter 205. The same genericinverters 205 are distributed to different countries, e.g., country 1-5,when ordered by customers. Because the generic inverters 205 may bestored in different warehouses, a country may receive inverters frommultiple warehouses. For instance, countries 1-4 receive the genericinverter 205 from both warehouses 110 and 115.

The generic inverters 205 are distributed to different countries andinstalled at different locations. Once installed at a particularlocation, the inverter is configured to comply with the local gridconnection standard in order to feed converted AC into the local powergrid. As illustrated in FIG. 2, because the inverters are configured atthe field after installation, it is possible to manufacture anddistribute a generic inverter that greatly simplifies the inventory anddistribution management of the inverters.

Several more detailed embodiments of the generic inverter that iscapable of being configured after installation are described in thesections below. Section I describes a typical installation of inverters.Next, Section II describes configuring inverters after they have beeninstalled. Section III describes several examples of inverterconfiguration. Next, Section IV describes an example of grid connectionstandard. Finally, Section V describes an electronic system thatimplements some embodiments of the invention.

I. Installation of Inverters

FIG. 3 conceptually illustrates a typical installation for an array ofinverters. As shown in the figure, an energy harvesting system 300harvests solar power from photovoltaic cells in solar panels. Theharvested solar energy is converted into electricity via an array 330 ofinverters 331-336, which are coupled to the solar panels 341-346 and areinstalled on a roof of a building 305. The inverters in the energyharvesting system 300 are also in a communication system 340 thatincludes a communication gateway 310, which gathers information from theinstalled array of inverters 330. The information gathered by thecommunication gateway 310 is then sent to a server 320 via a networksuch as the Internet 315. In some embodiments, the communicationsgateway 310 gathers information from the server 320 and/or the Internet315 and sends the information to the installed array of inverters 330.

The communication system 340 communicatively couples the inverters inthe array 330 with the communication gateway 310 and allows informationto be exchanged between devices in the communication system 340. In someembodiments, the communication system 340 is a wireless communicationsystem. The communication system 340 can be implemented in any one of anumber of wireless communication systems such as ZigBee, Wi-Fi,Bluetooth, Wireless MBus, etc. Though not illustrated, instead of or inaddition to wireless systems, some embodiments use power linecommunication, in which a data signal is modulated over a lowerfrequency carrier signal that is typical of mains voltage.

The communication gateway 310 is the hub of the communication system340. This is the case whether the communication system 340 is a wirelesssystem or a power line based system. The communication gateway 310 isalso referred to as the installation coordinator in some embodiments.The communication gateway 310 receives communication from some or all ofthe installed inverters in the system. In some embodiments, it alsoreceives communications from anchor nodes (not illustrated). Anchornodes are inverters or installation devices with known positions thatcan be used to ascertain the exact location of inverters. Thecommunication gateway 310 also sends information to the array ofinstalled inverters 330. In some embodiments, the communication gateway310 is equipped with computing components capable of analyzinginformation gathered from the inverters and/or the anchor nodes. Theresults of the analysis are then sent to the server 320. In someembodiments, the communication gateway 310 is capable of analyzinginformation gathered from the server 320 and/or the Internet 315. Theresults of the analysis are then sent to the array of installedinverters 330.

Because the communication gateway 310 is usually in close vicinity ofthe array of installed inverters 330, some embodiments use thecommunication gateway 310 to determine the physical location for thearray of installed inverters 330. The communication gateway 310 canconnect to the Internet 315 through many different communicationsystems. For example, the communication gateway 310 can connect to theInternet 315 through an Ethernet, a Wi-Fi network, a GSM network, orsome other communication systems. The communication gateway 310 is ableto determine its physical location through a set of parameters from thecommunication system that connects it to the Internet 315. For instance,the communication gateway 310 is able to determine its physical locationby the Internet Protocol (IP) address associated with it in someembodiments. The communication gateway 310 of some embodimentsdetermines its physical location through locating the nearest Wi-Fiaccess point or the nearest cellular tower, depending on the type ofcommunication system that connects it to the Internet 315.

For each determined physical location, there is a corresponding gridconnection standard that needs to be complied with by the inverters inorder to feed the generated AC into the local power grid. In someembodiments, the communication gateway 310 retrieves the appropriategrid connection standard based on the determined physical location andsends the grid connection standard to the array of installed inverters330. In some other embodiments, the communication gateway 310 sends thedetermined physical location to the array of inverters 330 and lets eachinverter to figure out applicable grid connection standard.

The server 320 receives data gathered or generated by the communicationgateway 310. The server 320 also receives data request from thecommunication gateway 310 and sends the requested data to thecommunication gateway. FIG. 3 illustrates the server 320 as beingaccessible by the communication gateway 310 via the Internet 315. Insome other embodiments (not illustrated), the server is accessible tothe communication gateway 310 by other means. For example, the server320 can be connected to the communication gateway via local areanetwork, via wired or wireless network. The server 320 and thecommunication gateway 310 can also reside on the same computing devicethat performs the functions of both the server 320 and the communicationgateway 310. In some embodiments, the database storage 325 resides onthe server 320. In other embodiments, the database storage 325 resideson a computing device separate from the server 320. The database storage325 stores the data collected from individual inverters, as well asother relevant data, e.g., a grid connection standards lookup table. Insome embodiments, the server 320 is part of a device (e.g., a computingdevice with display capabilities) that allows the viewing of the datacollected from the inverters at the server 320. In some embodiments, thecollected data is pushed up to a website or another server, which allowsend users to view the data.

The inverters in the array 330 such as inverters 331-336 receive DCvoltage generated by the solar photovoltaic panels and converts thereceived DC voltage into AC electricity. Descriptions of inverters canbe found in U.S. patent application Ser. No. 13/244,155, now publishedas U.S. Publication No. 2012/0057388, and U.S. patent application Ser.No. 13/244,161, and now published as U.S. Publication No. 2012/0063177.U.S. Publication No. 2012/0057388 and U.S. Publication No. 2012/0063177are hereby incorporated by reference. In addition to the componentsnecessary for converting DC voltage from solar panels to AC electricity,the inverters also include the components necessary for communicationswithin the communication network 340. In some embodiments, thecommunication components residing within the inverters (e.g., 331-336)are radio frequency (RF) circuitry for wireless communications with thecommunication gateway 310. In some embodiments, components for othermeans of communications (e.g., power line communications) are included.

In addition to using the wireless/RF system for communications, someembodiments also use the RF circuitry of the inverters for ascertainingthe location, or positioning of the inverters. In addition to sendinginformation of its own position, an inverter in some embodiments alsosends a unique identification (e.g., a serial number) to the server 320via the communication gateway 310. In some embodiments, each inverter ofthe array 330 receives a grid connection standard from the communicationgateway 310 or a handheld device (not illustrated) and configures itselfaccording to the grid connection standard in order to feed generated ACpower into the local power grid. In some embodiments, each inverterreceives a physical location from the communication gateway 310 or ahandheld device (not illustrated) and find out the applicable gridconnection standard based on the physical location by itself In someembodiments, each inverter of the array 330 contains a globalpositioning system (GPS) receiver and determines its physical locationbased on a GPS coordinate obtained by the GPS receiver. The inverterthen identifies applicable grid connection standard and configure itselfaccordingly. An example inverter will be described below by reference toFIG. 4.

The GPS is a global navigation satellite system (GNSS) that providesreliable location and time information in all conditions at all timesand from anywhere on Earth. In some embodiments, each anchor nodeincludes a GPS chip. In some embodiments, each inverter includes a GPSchip as well. The exact positions of the installed inverters can beexactly ascertained based on coordinates provided by the GPS chips inthe inverters.

The server 320 includes the storage 325, which is used to store datacollected from individual inverters and anchor nodes, as well as otherrelevant data, e.g., a grid connection standards lookup table. Acomputing device having access to the storage 325 can use the collecteddata to evaluate status of the inverters and perform other analysis oroperations. For example, a computing device having access to the storage325 can search for an appropriate grid connection standard for aparticular location. In some embodiments, such a computing device ispart of the server 320. In some embodiments, another computer separatefrom the server 320 performs the analysis. Such a computer can be acomputer in real-time communication with the communications system 340(e.g., being in a same network) such that the computer can perform theanalysis in real-time. Alternatively, such a computer can receive theinformation from the storage 325 at a later time via storage mediumssuch as flash drives. In addition to collecting information aboutinverters, some embodiments gather information about other componentssuch as power optimizers in the solar modules. The information of theseother components is also included in the analysis performed by theserver 320 or other computers.

II. Configuring Inverters After Installation

FIG. 4 illustrates a block diagram of an inverter 400 that can be usedto implement the array of inverters 330 of FIG. 3 (i.e., each of theinverters 331-336 can be implemented based on the inverter 400). Theinverter 400 converts DC voltage generated by photovoltaic cells 460into AC electricity for power grid 470. The inverter 400 also includescomponents necessary for configuring itself to comply with a local gridconnection standard and/or for communications within a communicationnetwork. The inverter 400 includes a processor 410, a transceiver(s)415, an antenna 490, a signal strength sensor 417, a read-only memory(ROM) 412, a random-access memory (RAM) 413, a serial number 420, areal-time clock 430, a GPS receiver 440, and a power converter 450.

The power converter 450 converts the DC voltage received from thephotovoltaic cell 460 to AC electricity for the power grid 470. In someembodiments, power converters are also referred to as power conditioningunits. Descriptions of power converters or power conditioning units canbe found in U.S. patent application Ser. No. 13/244,155, now publishedas U.S. Publication No. 2012/0057388, U.S. patent application Ser. No.13/244,161, now published as U.S. Publication No. 2012/0063177, and U.S.patent application 13/310,691, now published as U.S. Publication No.2012-0098346. In some embodiments, various components in the inverter400 (e.g., the processor 410 and the RF transceiver 415) are powered byenergy from the photovoltaic cell 460. In some of these embodiments, thesolar power is provided via the power converter 450.

Some of the operations performed by the power converter 450 aremonitored and controlled by the processor 410. In some embodiments, thepower converter 450 includes its own micro-controller(s) (notillustrated) for controlling the transfer of power from the PV cell 460to the power grid 470 (e.g., by controlling the transistor drivers inthe power converter 450), and the processor 410 monitors and controlsthe power converter 450 by communicating with the micro-controller(s) inthe power converter 450. In some other embodiments, the transfer ofpower in the power converter 450 is controlled by a micro-controller (orprocessor) that also controls the communications of the micro-inverter400.

In some embodiments, the processor 410 controls the operations performedby the power converter 450 based on a set of parameters stored in theROM 412. The set of parameters determines how the power converter 450should behave in converting power from DC to AC. The power converter 450performs different operations under the control of the processor 410when the set of parameters stored in the ROM 412 are different. Forexample, the power converter 450 complies with different grid connectionstandards when the set of parameters are set at different values. Thisenables the inverter 400 to be configured after installation by changingthe set of parameters stored in the ROM 412. In some embodiments, themicro-controller(s) (not illustrated) in the power converter 450accesses the set of parameters stored in the ROM 412 in order to controlthe operations performed by the power converter 450. For example, themicro-controller(s) use the set of parameters to control the transistordrivers in the power converter 450 differently in order to comply withlocal grid connection standard. In some embodiments, the ROM 412 is partof the power converter 450.

In some embodiments, the processor 410 controls the operations performedby the power converter 450 by executing a set of instructions stored inthe ROM 412. The set of instructions determines how the power converter450 should behave in converting power from DC to AC. The power converter450 performs different operations under the control of the processor 410when the set of instructions stored in the ROM 412 are different. Forexample, the power converter 450 complies with different grid connectionstandards when the set of instructions stored in the ROM 412 aredifferent. This enables the inverter 400 to be configured afterinstallation by changing the set of instructions stored in the ROM 412.In some embodiments, the micro-controller(s) (not illustrated) in thepower converter 450 executes the set of instructions stored in the ROM412 in order to control the operations performed by the power converter450. For example, the micro-controller(s) execute the set ofinstructions to control the transistor drivers in the power converter450 in order to comply with local grid connection standard. The RAM 413allows the processor 410 to access certain frequent used data quickly inany random order.

The RF transceiver 415 transmits and receives RF signals to and from oneor more other RF capable devices via the antenna 490. In the example ofFIG. 3, the RF transceivers in the inverters 331-336 transmit andreceive RF signals to and from the communications gateway 310. In someembodiments, the RF transceivers in the micro-inverters 331-336 transmitand receive RF signals to and from other micro-inverters in the array330 in a mesh-like manner. In some embodiments, the RF transceivers 415transmit and receive RF signals to and from anchor nodes forascertaining the position of the micro-inverter 400. In someembodiments, the RF transceiver 415 includes multiple RF transceiversfor transmitting and receiving RF signals to and from multiple RFcapable devices simultaneously.

In some embodiments, the RF transceiver 415 is used to communicate andexchange data with other devices in a RF communications network (e.g.,the communication network 340) via the RF signals being received. Insome of these embodiments, the inverters 331-336 communicate with thecommunication gateway 310 and/or other inverters in the array 330. Insome other embodiments, the RF receiver 415 is only used for determiningthe position of the inverter 400 but not for communications. In some ofthese embodiments, the inverter 400 includes one or more communicationscomponents (such as for performing power line communications) forsending and receiving data.

The signal strength sensor 417 measures the strength of the RF signalreceived by the RF transceiver 415. The signal strengths detected by thesignal strength sensors in individual inverters are used by someembodiments to determine the position of the inverters. In someembodiments, the inverter 400 performs received signal strengthindicator (RSSI) and/or link quality indicator (LQI) measurement basedon the RF signal received. In some of these embodiments, the signalstrength sensor 400 provides raw measurements to the processor 410 tocompute RSSI or LQI values. In some other embodiments, the inverter 400does not include the signal strength sensor 417, and the processor 410computes the RSSI or LQI readings directly based on the data received bythe RF transceiver 415.

The processor 410 controls the communication between the inverter 400and other devices. The processor 410 receives demodulated data from theRF transceiver 415. The processor 410 also produces data to be modulatedand transmitted by the RF transceiver 415. In addition to processingdata being transmitted or received by the RF transceiver 415, theprocessor 410 also receives readings provided by the signal strengthsensor 417, the real-time clock 430, the GPS receiver 440, and theserial number 420. The content of the real-time clock 430 in someembodiments can be updated by the processor 410 based on thecommunications with other devices. The processor 410 produces thetransmit data for the RF transceiver 415 based on some or all of thesereadings. In some embodiments that do not use the RF transceiver fordata communications, the processor 410 goes through anothercommunications component (e.g., a module for power line communications,not illustrated) for transmitting and receiving data.

In some embodiments, the processor 410 is a microprocessor that executesa set of instructions for producing the transmit data for the RFtransceiver 415. For example, in some embodiments, the processor 410composes data packets to be transmitted by the RF transceiver 415 basedon previously received data, the real-time clock (430), the serialnumber (420), the GPS coordinates (440), and the signal strength sensorreading (417). By receiving and transmitting these data, the inverter400 enables the energy harvesting system that includes the inverter toautomatically determine its location and identify an appropriate gridconnection standard to configure the inverter.

In some embodiments, the processor 410 also controls and monitors thepower converter 450. The processor 410 communicates with the powerconverter 450 and relays its status to other devices (e.g., thecommunication gateway 310) via the RF transceiver 415. In some otherembodiments, the power transfer operation and the communicationoperation are performed by a single micro-controller or microprocessor.

One of ordinary skill in the art will recognize that the diagram in FIG.4 is a conceptual representation of the components of an inverter. Thecomponents in a specific inverter may not be exactly the same asillustrated in this figure. For example, an inverter may not be equippedwith the GPS receiver 440 and the processor 410 could be an integratedpart of the power converter 450.

FIG. 5 conceptually illustrates an inverter configuration module 500 ofsome embodiments. Specifically, the figure illustrates an example ofconfiguring an inverter to comply with a grid connection standard basedon the installation location of the inverter. In some embodiments, theinverter configuration module 500 is a stand-alone software application,while in other embodiments the inverter configuration module 500 is partof an inverter operation control application. As shown, this figureillustrates a location identifier 510, a grid connection standardidentifier 520, a grid connection standards lookup table 525, and aconfiguration manager 530.

The location identifier 510 determines the installation location of theinverter and sends the location information 515 to the grid connectionstandard identifier 520. In some embodiments, the location identifier510 receives the installation location through a user interface 511. Theuser interface 511 receives the installation location through user inputand sends the location to the location identifier 510. In someembodiments, the location identifier 510 validates the user input and/orconverts the user input to a standard form before sending the locationinformation 515 to the grid connection standard identifier 520. In someembodiments, the location identifier 510 receives the installationlocation through a GPS receiver 512. The GPS receiver 512 receives a GPSsignal that identifies the installation location and forwards thelocation to the location identifier 510. In some embodiments, thelocation identifier 510 receives the installation location through anetwork interface 513. The network interface 513 connects the locationidentifier 510 to a communication network, e.g., the commutation network340 described above by reference to FIG. 3. As a result, the locationidentifier 510 is able to obtain the installation location from otherdevices in the communication network, e.g., the communication gateway310 described above by reference to FIG. 3, or a handheld installationdevice located nearby.

The communication gateway is able to determine its location through itsconnection to the Internet. Since the communication gateway is always inclose vicinity of the installed array of inverters, the location of thecommunication gateway can be treated as the location of the installedinverters. In some embodiments, a handheld installation device isconnected to each inverter in the array of installed inverters through awired connection or a short-range wireless connection. A user may inputthe installation location through the handheld installation device. Thatinstallation location is then transmitted to each installed inverter.The handheld installation device of some embodiments is equipped with aGPS receiver and can determine the current location of the handhelddevice through the GPS receiver. That location is then transmitted toeach installed inverter as the installation location of the invertersince the handheld device is in close vicinity of the installedinverters.

In some embodiments, the location identifier 510 uses a combination oftwo or more approaches to identify the installation location. Forexample, the location identifier 510 may receive an installationlocation identified by the communication gateway through the networkinterface 513 and confirm the location with user input received from theuser interface 511.

The grid connection standard identifier 520 receives the locationinformation 515 from the location identifier 510 and sends a gridconnection standard 522 to the configuration manager 530. The gridconnection standard identifier 520 identifies the grid connectionstandard 522 based on the received location information 515. In someembodiments, the grid connection standard identifier 520 queries thegrid connection standards lookup table 525 in order to find theapplicable grid connection standard for a particular location. The gridconnection standards lookup table 525 contains all the grid connectionstandards and the corresponding geographic regions for each gridconnection standard. In some embodiments, the grid connection standardslookup table 525 is located within the inverter. In other embodiments,the grid connection standards lookup table 525 is on a device separatedfrom the inverter and the grid connection standard identifier 520 uses acommunication network to communicate with that device in order to querythe grid connection standards lookup table 525.

The configuration manager 530 receives the grid connection standard 522and configures the inverter accordingly. In some embodiments, theconfiguration manager 530 stores the grid connection standard 522 as aset of parameters in a non-volatile memory (e.g., the ROM 412 asdescribed above by reference to FIG. 4) of the inverter and a controller(e.g., the processor 410 as described above by reference to FIG. 4)configures the power converting component (e.g., the power converter 450as described above by reference to FIG. 4) based on that set ofparameters. In some embodiments, the configuration manager 530 loads aunique set of instructions for each different grid connection standardfor executing by the controller or processor of the inverter.

An example operation of the inverter configuration module 500 will nowbe described by reference to FIG. 6. FIG. 6 conceptually illustrates aprocess 600 performed by some embodiments to configure an inverter tocomply with an appropriate grid connection standard based on theinstallation location of the inverter. In some embodiments, the process600 starts automatically when the inverter is installed and connected toa power line. In some embodiments, the process 600 starts when theinverter receives a command to start configuration.

As shown in the figure, the process determines (at 610) a location forthe installed inverter. As described above by reference to FIG. 5, theinstallation location can be determined by receiving a user inputtedlocation through a user interface, by receiving a GPS signal thatindicates the location of the inverter through a GPS receiver within theinverter, or by receiving a location through a network interface of acommunication network. The location received through the networkinterface comes from another device in the communication network, e.g.,the communication gateway 310 described above by reference to FIG. 3, ora handheld installation device located nearby. The communication gatewayis able to determine its location through its connection to theInternet. Since the communication gateway is always in close vicinity ofthe installed inverter, the location of the communication gateway can betreated as the location of the inverter.

In some embodiments, the handheld installation device is connected tothe inverter through a wired connection or a short-range wirelessconnection. A user may input the installation location through thehandheld installation device. The handheld installation device of someembodiments is equipped with a GPS receiver and can determine thecurrent location of the handheld device through the GPS receiver. Thatlocation is then transmitted to the inverter as the installationlocation of the inverter.

After determining the installation location for the inverter, theprocess 600 then identifies (at 615) a grid connection standard based onthe determined location. In some embodiments, the process 600 queries agrid connection standards lookup table in order to find the applicablegrid connection standard for the determined location. The gridconnection standards lookup table contains all the grid connectionstandards and the corresponding geographic regions for each gridconnection standard. In some embodiments, the grid connection standardslookup table is located within the inverter. In other embodiments, thegrid connection standards lookup table is on a device separated from theinverter and the process 600 query the grid connection standards lookuptable through a communication network.

Next, the process 600 configures (at 620) the inverter based on theidentified grid connection standard. In some embodiments, the process600 stores the identified grid connection standard as a set ofparameters in a non-volatile memory (e.g., the ROM 412 as describedabove by reference to FIG. 4) of the inverter to enable a processor orcontroller of the inverter to configure the power converting component(e.g., the power converter 450 as described above by reference to FIG.4) based on the set of parameters. In some embodiments, the process 600loads a unique set of instructions for the identified grid connectionstandard for executing by the controller or processor of the inverter.The process 600 then terminates.

One of ordinary skill in the art will recognize that the process 600 isa conceptual representation of the operations used to configure aninverter to comply with an appropriate grid connection standard based onthe installation location of the inverter. The specific operations maynot be performed in one continuous series of operations, and differentspecific operations may be performed in different embodiments.Furthermore, the process could be implemented using severalsub-processes, or as part of a larger macro process. For instance, insome embodiments, the process 600 is performed by one or more softwareapplications that execute on one or more devices.

III. Inverter Configuration Examples

Different embodiments use different approaches to configure an inverterafter installation. For example, some embodiments configure an array ofinverters installed in the same installation based on a grid connectionstandard identified by a communication gateway of the installation. Insome embodiments, an installer configures an array of installedinverters by pushing configuration data to each inverter using ahandheld device connected to the inverter through a wired connection ora short-range wireless connection. In some of these embodiments, theconfiguration data includes location information. In other embodiments,the configuration data includes a grid connection standard. The locationinformation is provided by the installer's manual input or by a GPSreceiver within the handheld device in some embodiments. In some otherembodiments, the configuration data includes a grid connection standard.Several detailed examples of inverter configuration will be describedbelow by reference to FIGS. 7-11.

A. Configuring Inverters Through a Communication Gateway

FIG. 7 conceptually illustrates a process 700 performed by someembodiments to configure a set of installed inverters through acommunication gateway. Details of a communication gateway are describedabove by reference to FIG. 3. In some embodiments, the process 700starts automatically when the set of installed inverter is connected toa communication gateway. In some embodiments, the process 700 startswhen the communication gateway receives a command to startconfiguration. As shown in FIG. 7, the process 700 determines (at 705) alocation of installation for a set of installed inverters based on a setof network connection parameters. In some embodiments, the set ofnetwork connection parameters is determined by the physical location ofthe communication gateway, because the communication gateway isphysically close to the installed inverters and its location can be usedas the installation location of the installed inverters.

The communication gateway can connect to the Internet through manydifferent communication systems. For example, the communication gatewaycan connect to the Internet through an Ethernet, a Wi-Fi network, a GSMnetwork, or some other communication systems. In some embodiments, thecommunication gateway determines its physical location through a set ofparameters associated with the communication system that connects it tothe Internet. For instance, the communication gateway in someembodiments determines its own physical location by its assigned IPaddress in the Internet. In some embodiments, the communication gatewaydetermines its own physical location based on the location of thenearest Wi-Fi access point or the nearest cellular tower.

The process 700 then identifies (at 710) a grid connection standard forthe determined physical location. In some embodiments, the process 700queries a grid connection standards lookup table in order to find theapplicable grid connection standard for the determined location. Thegrid connection standards lookup table contains all the grid connectionstandards and the corresponding geographic regions that utilize eachgrid connection standard. In some embodiments, the grid connectionstandards lookup table is located within the communication gateway. Insome other embodiments, the grid connection standards lookup table isstored in a device separated from the communication gateway and theprocess 700 query the grid connection standards lookup table through acommunication network.

Next, the process 700 selects (at 715) an inverter from the set ofinverters. The process 700 then sends (at 720) the identified gridconnection standard to the selected inverter in order to configure theinverter based on the grid connection standard. In some embodiments, theinverter stores the grid connection standard as a set of parameters in anon-volatile memory of the inverter and a controller configures thepower converting component of the inverter based on that stored set ofparameters. In some embodiments, the inverter loads a unique set ofinstructions for the grid connection standard for execution by acontroller or processor of the inverter.

The process 700 then determines (at 725) whether there are moreinverters that need to be configured. When there is at least one moreinverter that needs to be configured, the process 700 loops back to 715and selects another inverter from the set of inverters. When the process700 determines (at 725) that there is no more inverter that needs to beconfigured, the process terminates.

One of ordinary skill in the art will recognize that the process 700 isa conceptual representation of the operations used to configureinstalled inverters through a communication gateway. The specificoperations of the process 700 may not be performed in the exact ordershown and described. The specific operations may not be performed in onecontinuous series of operations, and different specific operations maybe performed in different embodiments. Furthermore, the process could beimplemented using several sub-processes, or as part of a larger macroprocess. For instance, in some embodiments, the process 700 is performedby one or more software applications that execute on one or morecomputers. In some embodiments, the communication gateway sends theidentified grid connection standard to multiple inverters at the sametime rather than sending it one by one. The process of some embodimentssends the determined location of the communication gateway to theinverters and let each inverter to figure out the applicable gridconnection standard.

B. Configuring Inverter Through Equipped GPS Receiver

In some embodiments, the communication gateway has no Internetconnection and an installed inverter has to configure itself by usingits own equipped GPS receiver.

FIG. 8 conceptually illustrates an installation for an array ofinverters that use equipped GPS receivers to configure themselves insome embodiments of the invention. As shown in the figure, an energyharvesting system 800 harvests solar power from photovoltaic cells insolar panels. The harvested solar energy is converted into electricityvia an array 830 of inverters, which are coupled to the solar panels andare installed on a roof of a building 805.

The inverters in the array 330 such as inverters 331-336 receive DCvoltage generated by the solar photovoltaic panels and convert thereceived DC voltage into AC electricity. Descriptions of inverters canbe found in the above mentioned U.S. patent application Ser. No.13/244,155, now published as U.S. Publication No. 2012/0057388, and U.S.patent application Ser. No. 13/244,161, and now published as U.S.Publication No. 2012/0063177.

For each determined physical location, there is a corresponding gridconnection standard that needs to be complied with by the inverters inorder to feed the generated AC into the local power grid. In someembodiments, each inverter of the array 330 is equipped with a globalpositioning system (GPS) receiver (such as GPS receivers 851-856) anddetermines its physical location based on a GPS coordinate obtained bythe GPS receiver. The inverter then identifies applicable gridconnection standard based on the physical location obtained through theGPS receiver. The inverter then configures itself according to theidentified local grid connection standard.

C. Manual Configuration

In some embodiments, the communication gateway is not connected to theInternet and the inverters are not equipped with GPS receivers. In someof these embodiments, an installer manually configures a set ofinstalled inverters by pushing configuration data to each inverter usinga handheld device. The handheld device connects to each inverter througha wired connection or a short-range wireless connection. FIG. 9conceptually illustrates using a handheld device to configure a set ofinstalled inverters. Specifically, this figure illustrates an installer901 carrying a handheld device (e.g., a mobile device) 920 that is usedas an installation or monitoring device for the inverters. As shown, thefigure illustrates an array 930 of inverters is installed on thebuilding 905 and an installer 901 carrying a handheld device 920 isconfiguring the array of inverters. The array of inverters 930 includessix inverters 931-936.

The installer 901 carries the handheld device 920 near the inverters inthe array 930. The handheld device 920 connects to each inverter in thearray 930 through a short-range wireless connection (e.g., Wi-Fi orBluetooth) or a wired connection. In some embodiments, the installer 901manually input a location into the handheld device 920. The handhelddevice 920 then identifies a corresponding grid connection standard forthe location and sends the grid connection standard to each inverter inthe array 930. Each inverter in the array 930 configures itself tocomply with the grid connection standard in order to feed its generatedpower into the local power grid. In some embodiments, the handhelddevice 920 simply sends the inputted location to each inverter in thearray 930 and let each inverter to figure out the appropriate gridconnection standard by itself. Each inverter in the array 930 thenconfigures itself to comply with the grid connection standard in orderto feed generated power into the local power grid.

FIG. 10 conceptually illustrates using a handheld device equipped with aGPS receiver to configure a set of installed inverters. Specifically,this figure illustrates an installer 901 carrying a handheld device 920equipped with a GPS receiver 1010 to configure the inverters. As shown,the figure illustrates an array of inverters 930 installed on thebuilding 905. An installer 901 is carrying a handheld device 920 andconfiguring the array of inverters 930. The array of inverters 930includes inverters 931-936. The handheld device 920 includes a GPSreceiver 1010.

The installer 901 carries the handheld device 920 near each of theinverter in the array 930. The handheld device 920 connects to eachinverter in the array 930 through a short-range wireless connection(e.g., Wi-Fi or Bluetooth) or a wired connection. Instead of manuallyinputting a location into the handheld device 920, the GPS reading ofthe GPS receiver 1010 determines the location of the handheld device920. The handheld device 920 is physically close enough to the array ofinverters 930 such that the location of the handheld device 920represents the location of the array of inverters 930.

In some embodiments, the handheld device 920 identifies a correspondinggrid connection standard for the determined location and sends the gridconnection standard to each inverter in the array 930. Each inverter inthe array 930 then configures itself to comply with the grid connectionstandard in order to feed its generated power into the local power grid.In some embodiments, the handheld device 920 simply sends the locationdetected by the GPS receiver 1010 to each inverter in the array 930 andlet each inverter to figure out the appropriate grid connection standardby itself. Each inverter in the array 930 then configures itself tocomply with the grid connection standard in order to feed generatedpower into the local power grid.

The handheld device 920 is equipped with GPS and can be carried to bephysically near any object. Such handheld device can be a Smart phone, aPDA, a GPS device, etc. When placed near an installed inverter, the GPSreading of the handheld device 920 can be transmitted to the installedinverter as the location of the inverter.

For some embodiments, FIG. 11 conceptually illustrates a process 1100performed by some embodiments to configure a set of installed invertersby a handheld device to comply with an appropriate grid connectionstandard. In some embodiments, the process 1100 starts automaticallywhen the handheld device is communicatively connected to the set ofinstalled inverters. In some embodiments, the process 600 starts whenthe handheld device receives a command to start configuration.

The process 1100 begins by determining (at 1105) a location ofinstallation for the set of installed inverters based on a user input ora GPS coordinate. In some embodiments, a user will tell the handhelddevice where the set of inverters are located (e.g., by manually input).In other embodiments, a GPS receiver equipped on the handheld devicewill provide a GPS coordinate of the handheld device. Since the handhelddevice is presumed to be in close proximity of the installed invertersduring this operation, the GPS coordinate of the handheld device canalso be treated as the location of the set of installed inverters.

The process 1100 then identifies (at 1110) a grid connection standardfor the determined location. In some embodiments, the process 1100queries a grid connection standards lookup table in order to find theapplicable grid connection standard for the determined location. Thegrid connection standards lookup table contains all the grid connectionstandards and the corresponding geographic regions that utilize eachgrid connection standard. In some embodiments, the grid connectionstandards lookup table is located within the handheld device. In otherembodiments, the grid connection standards lookup table is stored on adevice separated from the handheld device and the process 1100 queriesthe grid connection standards lookup table through a communicationnetwork.

Next, the process 1100 selects (at 1115) an inverter from the set ofinstalled inverters. The process 1100 then sends (at 1120) theidentified grid connection standard to the selected inverter in order toconfigure the inverter based on the grid connection standard. In someembodiments, the inverter stores the grid connection standard as a setof parameters in a non-volatile memory of the inverter and a controllerconfigures the power converting component of the inverter based on thatset of parameters. In some embodiments, the inverter loads a unique setof instructions for the grid connection standard for executing by acontroller or processor of the inverter.

The process 1100 then determines (at 1125) whether there are moreinverters need to be configured. When there are more inverters need tobe configured, the process 1100 loops back to 1115 and selects anotherinverter from the set of inverters. When the process 1100 determines (at1125) that there is no more inverter for configuration, the process 1100terminates.

One of ordinary skill in the art will recognize that the process 1100 isa conceptual representation of the operations used to configureinstalled inverters through a handheld device. The specific operationsof the process 1100 may not be performed in the exact order shown anddescribed. The specific operations may not be performed in onecontinuous series of operations, and different specific operations maybe performed in different embodiments. Furthermore, the process could beimplemented using several sub-processes, or as part of a larger macroprocess. For instance, in some embodiments, the process 1100 isperformed by one or more software applications that execute on one ormore computers. In some embodiments, the handheld device sends theidentified grid connection standard to multiple inverters at the sametime rather than sending it one by one. The process of some embodimentssends the determined location from the handheld device to the invertersand let each inverter to figure out the applicable grid connectionstandard.

IV. Grid Connection Standard

A grid connection standard includes a set of parameters that defines theregular behavior of a power grid and provides a guideline on the qualityof power in the power grid. FIG. 12 illustrates an example of a set ofparameters included in a grid connection standard. As illustrated in thefigure, a grid connection standard 1200 includes parameters such asvoltage 1205, voltage limits 1210, voltage unbalance 1215, voltage swell1220, voltage sag 1225, voltage fluctuation 1230, transient overvoltage1235, harmonics 1240, inter-harmonics 1245, high-order harmoniccomponent 1250, frequency 1255, frequency fluctuation 1260, electricalnoise 1265, interruption 1270, inrush current 1275, DC current injection1280, disconnection time 1285, reconnection time 1290, power factor1291, and power factor correction 1292.

A steady voltage 1205 is the voltage a customer can expect to receiveunder normal operating conditions. Since the loads on a power grid areconstantly changing, it is impossible to maintain a completely constantvoltage. Thus the voltage limits 1210 define a range, e.g., +5% and −8%,within which the deviation from the normal voltage 1205 should be in.

Voltage unbalance 1215 is generated by the increase or decrease of loadconnected to each phase, partial running equipment, voltage/currentwaveform distortion, voltage drop, or reverse phase voltage, etc. Thephenomenon may cause revolution faults, an increase in noise, and lesstorque in a motor. Thus the voltage unbalance 1215 should be limited to,e.g., 3% or less.

Voltage swell 1220 is the instantaneous voltage increase caused bylightning strikes, opening or closing of a power supply circuit, highcapacitor bank switching, ground short circuit, or cutting a heavy load,etc. It may also occur due to the grid connection of a new energy source(solar power, etc.). A sudden increase in voltage may damage or resetthe power supply of equipment. Voltage sag 1225 is an instantaneousvoltage drop caused by the cutting off of the power supply circuit dueto a short circuit to the ground or high inrush current generation whenstarting a large motor, etc. The voltage sag 1225 may cause a stop orreset of equipment, turning off lighting, speed change or stop of motor,and synchronization error of synchronous motors or generators. Thus fastacting voltage regulators or power conditioners may be needed to protectsensitive equipment from the voltage swell 1220 and the voltage sag1225.

Voltage fluctuation (flicker) 1230 is a periodically repeated voltagefluctuation caused by a furnace, arc welding or thyristor controlledload. It may cause lights to flicker and equipment to malfunction. Thusa limit may be placed to limit the frequency of occurrence for voltagefluctuation 1230.

Transient overvoltage (impulse) 1235 is the voltage change generated bya lightning strike, contact problem and closing of a circuitbreaker/relay. It is often a rapid change and consists of high peakvoltage. Damage to an equipment's power supply or reset function oftenoccurs near the generation point due to its high voltage. Therefore,surge suppression equipment or other measures may need to be taken toprotect against damage and malfunction due to transient overvoltage1235.

Harmonics 1240 are generated by semiconductor control devices in thepower supply of equipment as a result of distorted voltage and currentwaveforms. When the harmonic component is big, it may cause seriousaccidents such as overheating or noise in motors or transformers, burnout reactors in phase compensation capacitors, etc. Inter-harmonics 1245are generated by a voltage/current waveform distortion caused by anelectronic frequency converter, cycle converter, Scherbius system,inductive motor, welder or arc furnace, etc., and consists ofnon-integer orders of the fundamental frequency. Inter-harmonics 1245may cause damage, malfunction or deterioration of equipment due to thezero-cross shift of the voltage waveform. High-order harmonic component1250 is a noise component higher than several kHz generated by thesemiconductor control device in the power supply of equipment, and maycontain various frequency components. High-order harmonic components1250 may damage the power supply of equipment, reset equipment orintroduce abnormal noise in equipment such as TVs or radios. Thuslimitations, e.g., harmonic voltage limits and harmonic currentdistortion limits, may be imposed to protect against damage andmalfunction due to harmonics 1240, inter-harmonics 1245, and high-orderharmonic component 1250.

A power grid needs to maintain a normal frequency 1255 that should notvary more than a very small range, e.g., 0.05 Hertz from 60 Hertz.Frequency fluctuation 1260 occurs due to a change of effective powerbalance between supply and consumption, or an excessive increase ordecrease of the load. Measures need to be taken to prevent frequencyfluctuation 1260 in order to maintain a steady normal frequency 1255.

Electrical noise 1265 is unwanted electrical signals with broadbandspectral content lower than 200 kHz superimposed upon the phase orneutral conductors or signal lines. Power electronic devices, controlcircuits, arcing equipment, loads with solid-state rectifiers, andswitching power supplies can cause noise 1265 in power systems. Noiseproblems are often made worse by improper grounding. Thus measures suchas employing proper grounding techniques and installing filters,isolation transformers, and line conditioners may need to be taken tomitigate the impact of electrical nose 1265.

Interruption 1270 is a power outage over an instantaneous, short or longperiod. It is caused by accidents such as lightning strikes or trippingof the circuit breaker because of a short circuit. Inrush current 1275is an instantaneous high current flowing at the time equipment ispowered on. Inrush current 1275 may cause relays to malfunction, circuitbreakers to open, impact on the rectifier, unstable power supplyvoltage, and/or equipment to malfunction or rest. A grid connectionstandard may require taking remedial measures in dealing withinterruption 1270 and inrush current 1275.

Single-phase voltage source inverters are used for connectingsmall-scale renewable energy sources to the low voltage distributionnetwork. They operate to supply the network with sinusoidal current. Ifoutput transformers are not used, these inverters must prevent excessiveDC current injection 1280, which may cause detrimental effects in thenetwork. Therefore, a grid connection standard may contain requirementsregarding DC current injection 1280.

The disconnection time 1285 specifies how fast the grid connection of anenergy source (e.g., an inverter) needs to disconnect in the case of thegrid going down in a number of milliseconds. The reconnection time 1290specifies how fast, e.g., within how many seconds, the grid connectionof the energy source needs to reconnect with the grid afterdisconnecting from the grid.

The power factor 1291 of an AC electrical power system is defined as theratio of the real power flowing to the load to the apparent power in thecircuit, and is a dimensionless number between 0 and 1. Real power isthe capacity of the circuit for performing work in a particular time.Apparent power is the product of the current and voltage of the circuit.Due to energy stored in the load and returned to the source, or due to anon-linear load that distorts the wave shape of the current drawn fromthe source, the apparent power will be greater than the real power.

Power factor correction 1292 brings the power factor of an AC powercircuit closer to 1 by supplying reactive power of opposite sign, addingcapacitors or inductors that act to cancel the inductive or capacitiveeffects of the load, respectively. The reactive elements can createvoltage fluctuations and harmonic noise when switched on or off. Theywill supply or sink reactive power regardless of whether there is acorresponding load operating nearby, increasing the system's no-loadlosses. In the worst case, reactive elements can interact with thesystem and with each other to create resonant conditions, resulting insystem instability and severe overvoltage fluctuations. As such,reactive elements cannot simply be applied without engineering analysis.

V. Electronic System

Many of the above-described features and applications are implemented assoftware processes that are specified as a set of instructions recordedon a computer readable storage medium (also referred to as computerreadable medium). When these instructions are executed by one or morecomputational or processing unit(s) (e.g., one or more processors, coresof processors, or other processing units), they cause the processingunit(s) to perform the actions indicated in the instructions. Examplesof computer readable media include, but are not limited to, CD-ROMs,flash drives, random access memory (RAM) chips, hard drives, erasableprogrammable read only memories (EPROMs), electrically erasableprogrammable read-only memories (EEPROMs), etc. The computer readablemedia does not include carrier waves and electronic signals passingwirelessly or over wired connections.

In this specification, the term “software” is meant to include firmwareresiding in read-only memory or applications stored in magnetic storagewhich can be read into memory for processing by a processor. Also, insome embodiments, multiple software inventions can be implemented assub-parts of a larger program while remaining distinct softwareinventions. In some embodiments, multiple software inventions can alsobe implemented as separate programs. Finally, any combination ofseparate programs that together implement a software invention describedhere is within the scope of the invention. In some embodiments, thesoftware programs, when installed to operate on one or more electronicsystems, define one or more specific machine implementations thatexecute and perform the operations of the software programs.

FIG. 13 conceptually illustrates an electronic system 1300 with whichsome embodiments of the invention are implemented. The electronic system1300 may be a computer (e.g., a desktop computer, personal computer,tablet computer, etc.), phone, PDA, or any other sort of electronicdevice. Such an electronic system includes various types of computerreadable media and interfaces for various other types of computerreadable media. Electronic system 1300 includes a bus 1305, processingunit(s) 1310, a graphics processing unit (GPU) 1315, a system memory1320, a network 1325, a read-only memory (ROM) 1330, a permanent storagedevice 1335, input devices 1340, and output devices 1345.

The bus 1305 collectively represents all system, peripheral, and chipsetbuses that communicatively connect the numerous internal devices of theelectronic system 1300. For instance, the bus 1305 communicativelyconnects the processing unit(s) 1310 with the read-only memory 1330, theGPU 1315, the system memory 1320, and the permanent storage device 1335.

From these various memory units, the processing unit(s) 1310 retrievesinstructions to execute and data to process in order to execute theprocesses of the invention. The processing unit(s) may be a singleprocessor or a multi-core processor in different embodiments. Someinstructions are passed to and executed by the GPU 1315. The GPU 1315can offload various computations or complement the image processingprovided by the processing unit(s) 1310. The read-only-memory ROM 1330stores static data and instructions that are needed by the processingunit(s) 1310 and other modules of the electronic system. The permanentstorage device 1335, on the other hand, is a read-and-write memorydevice. This device is a non-volatile memory unit that storesinstructions and data even when the electronic system 1300 is off. Someembodiments of the invention use a mass-storage device (such as amagnetic or optical disk and its corresponding disk drive) as thepermanent storage device 1335.

Other embodiments use a removable storage device (such as a floppy disk,flash memory device, etc., and its corresponding disk drive) as thepermanent storage device. Like the permanent storage device 1335, thesystem memory 1320 is a read-and-write memory device. However, unlikestorage device 1335, the system memory 1320 is a volatile read-and-writememory, such a random access memory. The system memory 1320 stores someof the instructions and data that the processor needs at runtime. Insome embodiments, the invention's processes are stored in the systemmemory 1320, the permanent storage device 1335, and/or the read-onlymemory 1330. For example, the various memory units include instructionsfor processing multimedia clips in accordance with some embodiments.From these various memory units, the processing unit(s) 1310 retrievesinstructions to execute and data to process in order to execute theprocesses of some embodiments.

The bus 1305 also connects to the input and output devices 1340 and1345. The input devices 1340 enable the user to communicate informationand select commands to the electronic system. The input devices 1340include alphanumeric keyboards and pointing devices (also called “cursorcontrol devices”), cameras (e.g., webcams), microphones or similardevices for receiving voice commands, etc. The output devices 1345display images generated by the electronic system or otherwise outputdata. The output devices 1345 include printers and display devices, suchas cathode ray tubes (CRT) or liquid crystal displays (LCD), as well asspeakers or similar audio output devices. Some embodiments includedevices such as a touchscreen that function as both input and outputdevices.

Finally, as shown in FIG. 13, bus 1305 also couples electronic system1300 to a network 1325 through a network adapter (not shown). In thismanner, the computer can be a part of a network of computers (such as alocal area network (LAN), a wide area network (WAN), or an Intranet, ora network of networks, such as the Internet. Any or all components ofelectronic system 1300 may be used in conjunction with the invention.

Some embodiments include electronic components, such as microprocessors,storage and memory that store computer program instructions in amachine-readable or computer-readable medium (alternatively referred toas computer-readable storage media, machine-readable media, ormachine-readable storage media). Some examples of such computer-readablemedia include RAM, ROM, read-only compact discs (CD-ROM), recordablecompact discs (CD-R), rewritable compact discs (CD-RW), read-onlydigital versatile discs (e.g., DVD-ROM, dual-layer DVD-ROM), a varietyof recordable/rewritable DVDs (e.g., DVD-RAM, DVD-RW, DVD+RW, etc.),flash memory (e.g., SD cards, mini-SD cards, micro-SD cards, etc.),magnetic and/or solid state hard drives, read-only and recordableBlu-Ray® discs, ultra density optical discs, any other optical ormagnetic media, and floppy disks. The computer-readable media may storea computer program that is executable by at least one processing unitand includes sets of instructions for performing various operations.Examples of computer programs or computer code include machine code,such as is produced by a compiler, and files including higher-level codethat are executed by a computer, an electronic component, or amicroprocessor using an interpreter.

While the above discussion primarily refers to microprocessor ormulti-core processors that execute software, some embodiments areperformed by one or more integrated circuits, such as applicationspecific integrated circuits (ASICs) or field programmable gate arrays(FPGAs). In some embodiments, such integrated circuits executeinstructions that are stored on the circuit itself. In addition, someembodiments execute software stored in programmable logic devices(PLDs), ROM, or RAM devices.

As used in this specification and any claims of this application, theterms “computer”, “server”, “processor”, and “memory” all refer toelectronic or other technological devices. These terms exclude people orgroups of people. For the purposes of the specification, the termsdisplay or displaying means displaying on an electronic device. As usedin this specification and any claims of this application, the terms“computer readable medium,” “computer readable media,” and “machinereadable medium” are entirely restricted to tangible, physical objectsthat store information in a form that is readable by a computer. Theseterms exclude any wireless signals, wired download signals, and anyother ephemeral signals.

While the invention has been described with reference to numerousspecific details, one of ordinary skill in the art will recognize thatthe invention can be embodied in other specific forms without departingfrom the spirit of the invention. In addition, a number of the figures(including FIGS. 6, 7, and 11) conceptually illustrate processes. Thespecific operations of these processes may not be performed in the exactorder shown and described. The specific operations may not be performedin one continuous series of operations, and different specificoperations may be performed in different embodiments. Furthermore, theprocess could be implemented using several sub-processes, or as part ofa larger macro process. Thus, one of ordinary skill in the art wouldunderstand that the invention is not to be limited by the foregoingillustrative details, but rather is to be defined by the appendedclaims.

What is claimed is:
 1. An energy harvesting system comprising: a powerconverter for converting DC power from a photovoltaic device to AC powerfor delivery to an AC grid; and a server communicatively coupled to thepower converter and configured to determine an AC grid connectionstandard for the power converter.
 2. The energy harvesting system ofclaim 1 wherein the server determines the AC grid connection standardbased on a physical location of the power converter.
 3. The energyharvesting system of claim 2 wherein the server determines the AC gridconnection standard in response to receiving GPS data from the powerconverter.
 4. The energy harvesting system of claim 1 wherein the serverdetermines the AC grid connection standard based on a user input.
 5. Theenergy harvesting system of claim 1 including a gateway thatcommunicates information between the power converter and the server. 6.The energy harvesting system of claim 5 wherein the gateway is locatedproximate the power converter and determines a physical location of thegateway that is communicated to the server.
 7. The energy harvestingsystem of claim 6 wherein the gateway determines the physical locationof the gateway based on a set of network connection parameters.
 8. Theenergy harvesting system of claim 1 wherein the server communicates theAC grid connection standard to the power converter, and in response thepower converter configures itself to be compatible with the AC gridconnection standard.
 9. An energy harvesting system comprising: a powerconverter for converting DC power from a photovoltaic device to AC powerfor delivery to an AC grid; and a gateway configured to communicativelycouple the power converter to a server and to transmit AC gridconfiguration information from the server to the power converter. 10.The energy harvesting system of claim 9 wherein the AC gridconfiguration information is determined by the server.
 11. The energyharvesting system of claim 9 wherein the AC grid configurationinformation includes a physical location of the power converter.
 12. Theenergy harvesting system of claim 9 wherein the AC grid configurationinformation is transmitted to the power converter in response to thepower converter transmitting a GPS coordinate to the server through thegateway.
 13. The energy harvesting system of claim 12 wherein the powerconverter includes a GPS receiver that generates the GPS coordinatebased on a physical location of the power converter.
 14. The energyharvesting system of claim 9 wherein the AC grid configurationinformation is received from a user input into the server.
 15. Theenergy harvesting system of claim 9 wherein the AC grid configurationinformation is received from a handheld device.
 16. A power converterfor a photovoltaic power system, the power converter comprising: powerconversion circuitry configured to convert DC power received from aphotovoltaic device to AC power for delivery to an AC grid; and controlcircuitry configured to receive AC grid configuration information and inresponse, reconfigure the power conversion circuitry according to the ACgrid configuration information.
 17. The power converter of claim 16wherein the AC grid configuration information is related to a physicallocation of the power converter.
 18. The power converter of claim 16wherein the AC grid configuration information is received in response tothe power converter transmitting physical location data to a server. 19.The power converter of claim 18 further including GPS circuitryconfigured to generate the physical location data corresponding to aphysical location of the power converter.
 20. The power converter ofclaim 16 wherein the AC grid configuration information is received inresponse to a user inputting data in a server that communicates with thepower converter.